These data come from the Archives of musculoskeletal tumor and pseudotumoral lesions of the Istituto Ortopedico Rizzoli in Bologna. We do not report incidence data, but frequency data registered at a referral center for musculoskeletal lesions. From September 1900 to December 2014, the archive comprises 28,477 cases, of which 790 (2.77%) were lesion of the sacrum. To better understand the specifcity of sacrum lesions, data will be compared to the fgures of bone lesions affecting the whole skeleton.